Smoothing variable-bit-rate video in an internetwork

The burstiness of compressed video complicates the provisioning of network resources for emerging multimedia services, For stored video applications, the server can smooth the variable-bit-rate stream by transmitting frames i nto the client playback buffer in advance of each burst. Drawing on prior k nowledge of the frame lengths and client buffer size, such bandwidth-smooth ing techniques can minimize the peak and variability of the rate requiremen ts while avoiding underflow and overflow of the playback buffer. However, i n an internetworking environment, a single service provider typically does not control the entire path from the stored-video server to the client buff er. This paper presents efficient techniques for transmitting variable-bit- rate video across a portion of the route, front an ingress node to an egres s node. We develop efficient techniques for minimizing the network bandwidt h requirements by characterizing how the peak transmission rate varies as a function of the playback delay and the buffer allocation at the two nodes. Drawing on these results, we present an efficient algorithm for minimizing both the playback delay and the buffer allocation, subject to a constraint on the peak transmission rate. We then describe how to compute an optimal transmission schedule for a sequence of nodes by solving a collection of in dependent single-link problems, and show that the optimal resource allocati on places all buffers at the ingress and egress nodes. Experiments with mot ion-JPEG and MPEG traces show the interplay between buffer space, playback delay, and bandwidth requirements for a collection of full-length video tra cts.